In Situ Strength Testing of Temporary Steel Guardrails Installed on Existing Flat-Roof Parapets.

The installation of guardrails around a roof perimeter is an efficient way to protect construction workers against falls from heights, provided the guardrails are strong enough to arrest a fall. A guardrail's strength relies heavily on its fastening to the roof parapets, and an improper fastening could lead to unsafe guardrails. This article investigates the in situ strength of temporary steel guardrails installed on the flat roof parapets of two existing buildings, respectively built in 2008 and 2013. Thirty-six strength tests were conducted on three different guardrails and four different parapets, considering different methods of fastening the vertical posts to the parapets and varying the fastening hardware. The results show that some guardrails are not easily installed on smaller roof parapets, which could lead to improper installation on some work sites. Fastening using only one plane of the parapet often resulted in guardrails failing before reaching the regulatory strength requirement. Fastening using two planes of the parapets gave satisfactory results in comparison, and that should be the preferred fastening method to guarantee workers' safety. [ABSTRACT FROM AUTHOR]